Fire indicating system



Oct. 22, 1935. w. D. LINDSEY FIRE INDICATING SYSTEM Filed June 4, 1931 a a /l\ 15 9 g S Z INVENTOR Z I J'W d'l l J5 W,M* 5 if ATTORNEY Patented Oct. 22, 1935 UNITED STATES PATENT OFFiCE FIRE INDICATING SYSTEM Application June 4, 1931, Serial No. 542,004

4 Claims.

My invention relates to a system for detecting or indicating the occurrence or presence of fire or other high temperature condition.

' My invention has reference to a system utilizable for indicating a fire condition on a freight,

baggage, express car, or the like.

My invention has particular reference to a fire indicating system for any suitable movable vehicle or the like, the arrangement being such that the temperature responsive device of said vehicle may be connected into circuit with a stationary fire indicating or control system when said Vehicle has been brought to rest in a storage space,

depot or the like.

Further objects, advantages and characteristics of my invention will become apparent from the following description taken 'in connection with the accompanying drawing.

My invention resides in the systems, arrangement, combination and features of construction of the character hereinafter described and claimed. 7

For an understanding of my invention and for an illustration of some of the embodiments thereof, reference is to be had to the accompanying drawing, in which:

Figure 1 is a perspective view of a freight car having associated therewith a fire indicating systern in accordance with my invention;

* Fig. 2 is a diagram of circuit connections for the fire indicating system of Fig. 1;

Fig. 3 is a transverse vertical sectional view of a fire detecting cable; and

,7 Fig. 4 is a diagram of circuit connections illustrating the system of Fig. 2 in combination with a supervised fire detecting system.

' Referring to Fig. 1, A represents any suitable vehicle, conveyance or the like which for purposes of explanation of my invention, has been 40 illustrated as an ordinary freight car although, by no means at all, is my invention to be thus limited.

It is well known that freight cars are often used for transporting valuable goods of inflammable character or goods of such character that spontaneous combustion is apt to develop therein. Where a car carrying valuable 'goods as noted above is one of a long train of cars, a fire condition is apt to develop and long persist before knowledge thereof comes toan employee of the railroad either on the train or at a wayside station. By that time, the contents of the car may be more or less of a total loss and the fire condition may even have developed sufficiently to endanger other cars of the train or property along the roadside. In accordance with one phase of my'invention, a suitable arrangement is provided for promptly indicating the presence of a fire condition on a car equipped as proposed by me 5 so that steps may be immediately taken to overcome the dangerous condition.

With this end in view, a suitable temperature responsive device is disposed interiorly of the car A and, by preference, this temperature responsive device is a desired length of fire detectlng cable C'such, for example. as disclosed in my pending application Serial No. 352,624, filed April 5, 1929. As clearly disclosed in said application and as disclosed herein in Fig. 3, said cable C may comprise a. core I disposed within a tube or sleeve 2 longitudinally slotted as indicated at 20.. Disposed upon the sleeve 2 is a layer of insulating material 3 formed, preferably by winding a plurality of fabric strands upon the aforesaid sleeve 2. Encircling the insulating layer 3 is a suitable sheath 4 which carries a waterproof cover 5 having a fabric layer B disposed thereupon.

The aforesaid core I is formed from any suitable metallic material adapted to become molten 5 when elevated in temperature to a predetermined extent as may be effected when said core I is exposed to radiated heat coming from a high temperature area such, for example, as may be occasioned by a fire condition occurring in the so neighborhood of the cable C. The core I, then, is a good conductor of electricity and the same is true of the sheath 4, said core I and sheath 4 forming sides of an electrical circuit separated by the insulation 3. Upon occurrence of an ambient temperature increase of predetermined magnitude, the core I becomes molten and expands laterally through the insulation 3 so as to come into contact with the sheath 4 whereby the cable conductors are short-circuited.

In accordance with my invention, a suitable length of the aforesaid cable 0 is so disposed as to extend into any suitable region of the car A. As herein shown although not necessarily, such length of the cable C is disposed interiorly of the car roof, the cable being held in fixed position in any suitable manner.

With the cable thus held in fixed position and shown more particularly in Fig. 2, conductors a and b are connected, respectively, to the aforesaid core I and sheath 4, the conductor a leading to one terminal of a storage battery 0 or other suitable source of electrical energy, the conductor b leading to the other terminal of said battery 0.

Included in the circuit formed by the conductors a and b are one or more signal devices d which preferably and as herein illustrated are incandescent electric lamps designed to be fully illuminated by the battery 0.

In accordance with my invention, although not necessarily, a pair of the lamps d are utilized. Whether or not the arrangement is of this character, it is highly desirable that one lamp cl be so disposed that it extends well above the upper surface of the car roof, it also being desirable that a lamp d be disposed late-rally with respect to the side of the car. Preferably, the lamps d are exposed both at the front and rear whereby they are visible both from the front and rear of the train. Furthermore, said lamp cZ should have eachlight path spanned by transparent sheet material of amber or other color significantly dif ferent from the red and green signals customarily used in railroad work.

With a car A equipped as described above, the circuit including the lamps d and extending from the terminals of the battery is normally open. Accordingly, the lamps it normally are nonluminous. However, should a fire condition develop in the material contained in the car A, heat is transmitted to the core I of the cable 0 and the latter becomes molten when elevated sufliciently in temperature. When this happens, the core and sheath 4 are short-circuited, whereby the circuit from the terminals of the battery 0 which includes the lamps d is closed or completed. As a result, the lamps d are energized.

In freight train operation, it is'customary for 1 an attendant of the train to sit in the upper part of the caboose so that he observe the cars in front of him. Thus, the lamp d extending above the roof of any car A equipped in accordance with my invention is in the direct field of vision of the aforesaid attendant. As a result, it follows that the occurrence of a fire condition on any car A is quite apt to be promptly observed. Furthermore, the'disposition of a lamp (1 laterally of a car side is of importance because placing such a '7 lamp in the field of vision of a train attendant looking forwardly of the train along the side thereof or of the engineman or fireman when the latter look rearwardly.

Furthermore, a lamp or lamps d disposed in accordance with my invention are in such position that they are readily observable by a tower attendant. Therefore, should a fire condition have developed and escaped attention of someone on the train, it is more: than likely that the same will be observed by some tower or signal attendant who of course will immediately issue a warning concerning the fire condition.

Ordinarily, the cable C is supported interiorly of the car solely by clamps or the like. The conductors a and b forming the battery and lamp circuit may extend through suitable conduits if desired.

A fire detecting system of the character described above affords satisfactory protection for a car A while in transit. When the latter is to be stored or disposed in a yard, depot, or the like for any length of time, it is highly desirable that a supplementary protective arrangement be provided and this is true, more particularly, when a number of cars A are to be disposed in the same yard or depot, and it is desired that they be brought effectively under the observation of a watchman or the like located more or less distantly from said yard or depot.

In accordance with this broad and important phase of my invention, the fire detecting cable C on the car A is adapted to be connected into a suitable stationary signalling or control circuit which is of the supervised type. To this end, the car A may carry a contact-making de- I 5 pair of said contact elements being connected by conductors f and y to the core I and sheath 4, respectively, at one end of the cable C, the aforesaid conductor a being connected to the contact element of the other pair of contact elements, and a conductor h leading from the sheath 4 at the other end of the cable C to the other contact Y element of said other pair of contact elements. Associated with that contact element to which the conductor a is connected is a contact member al connected by a conductor 0.2 tothe same terminal of the battery 0 as the conductor a is connected to in Fig. 2.

Normally, the contact member al engages its contact element so that the circuit is complete between the conductors w and a2. However, the circuit between these two conductors a and. a2 is adapted to be broken when a suitable plug is associated with the receptacle 6 as hereinafter described.

Adapted for association with the receptacle e is a plug a! which preferably comprises blade con- .tact members adapted to be slidably related to the respective contact elements of said receptacle e. Connected to the plug el is a cable K, the conductors 8, Ill, 9 and 'l of which are connected to the respective blade contact members of said plug at. The conductors 8, l0, 9 and 1 lead to any suitable control and signal circuit which as herein illustrated, but not necessarily, is of the character disclosed in my pending application 0 Serial No. 388,148, filed August 24, 1929. The relays, signal devices, etc. of said control and signal circuit may be mounted on a panel, not shown, disposed in an oiiice, watchmans booth or other space either within, without or far removed from the aforesaid yard or depot in which the car A is stored. a

In accordance with my invention, a car A, as soon as it is brought to the aforesaid yard or depot,.has a plug 6! associated with the receptacle e carried thereby. The plug el is so de' signed that the blade contact member which is to be associated with the contact element to which lead the conductors a and a2 is operative, when the plug 6! is inserted in the receptacle e, to automatically open the prior existing circuit between contact member al and. its associated contact element, this prior existing circuit being automatically reestablished by closure of the contact member a! upon its associated contact element when the plug el is withdrawn from the receptacle It results, therefore, that the act of inserting the plug 6! into the receptacle e automatically opens the circuit of the battery 0 and lamps d, this being the hereinbefore described signaling circuit adapted for use during transit of the car A. As a further result of the insertion of the plug 2! into the receptacle 6, the cable section C on the car A is inserted in the circuit including the conductors 8, ill, 9 and I. That is, the core I and sheath 4, at one end of said cable section C, are connected by the respective conductors a. and h to the conductors 6 and it, while the core i and sheath 4, at the other end of said cable section C, are connected by the respective conductors f and g to the conductors l and 8. The fire detecting cable on the car A is thereby connected in the supervised circuit now to be described whereby an alarm will be given in the event that a fire condition should develop on the car A while it is in the storage yard or depot.

As stated above, the herein described supervised circuit is of the character disclosed in my pending application Serial No. 383,148, filed August 24, 1929, and that circuit comprises relays R, Ri, R2 and R3. The conductors I and 8 terminate in and include the winding of relay R. The conductor 9 includes the armature H of relay R! and is connected to one terminal of a suitable source of electrical energy E. The co ductor It includes the winding of relay R2 and is connected to the other terminal of said source of electrical energy E. The winding of relay R5 is connected across the aforesaid conductors Q and I0 and hence across said source of electrical energy E.

A second source of electrical energy E! has the respective conductors l2 and 13 connected to the terminals thereof. Conductor i2 is connected to the aforesaid conductor ll! while the conductor I3 terminates in a contact coactable with the armature H of relay Rl.

Connected to the terminals of a suitable signal device S are the respective conductors I4 and I5. Conductor I 4 terminates in a contact coactable with an armature IQ of the relay RI while the conductor I5 is connected to the aforesaid con ductor l3.

The relay R2 comprises armatures H and it. Conductors i9 and 29 terminate in contacts coactable, respectively, with said armatures El and l 8, said conductors l 9 and 2% including the winding of relay R3.

A conductor 2! terminates in a contact coactable with the aforesaid armature l8, said conductor 2| leading to one terminal of a suitable signal device Si, the other terminal of which is connected by a conductor 22 to one terminal of another signal device S2. The other terminal of the latter is connected to a conductor 23 leading to and connected to the aforesaid conductor 9. An extension of the conductor 23 leads to and is connected to an armature 24 of the aforesaid relay R3.

The relay R comprises an armature 25 to which is connected a conductor 26 leading to the armature i! of relay R2 and also to the conductor 9.

A conductor 2? comprises contacts coactable, respectively, with the armature 25 of relay R and with the armature 24 of relay R3. Connected to the conductor 2? is a conductor 28 leading to one terminal of a suitable signal device S3, the other terminal of which is connected, by a conductor I 7 to the conductors l9 and 2| lead to an auxiliary other source of therewith; and when the voltage of the source of electrical energy is at a proper value and that the circuit thereof is not open.

The herein described source of electrical energy E may be, and ordinarily is, an ordinary six volt 5 storage battery. This battery E constitutes the main source of supply of electrical energy, the

electrical energy E4 being supplementary and utilizable, if desired, in the event that the voltage of the main battery E decreases 10 to an abnormal extent; ordinarily, the supplementary battery E5 may comprise a plurality of cells suitably connected whereby the voltage thereacross is substantially six volts.

A circuit arrangement or" the character herein- 15 before described involves a plurality of semi-independent circuits so arranged that there may be electrical supervision of (1) the fire detecting cable C and equipment associated directly therewith; (2) the various signals; and (3) the source 20.

of electrical energy E. Further and primarily, the circuit arrangement is such that an indication or other control function is obtained in the event that the core l becomes molten.

Cable supervision 25 As hereinbefore described, the conductor 9 extends from one terminal of the battery E and is connected to the core i of cable C, the conductor 1 also connected to said core l leading to one terminal of the winding of relay R, the other terminal of which is connected to the sleeve 5 of cable C by the conductor 8, said sleeve t being connected to the conductor it which leads back to the other terminal of the battery E. In this circuit, the armature ii of relay RE is included, as are the windings of relays R and R2. The windingcharacteristics of relays R and R2, however, are different and so arranged that the current flow is suflicient to cause the relay R to be operated, but 40 insufiicient to cause the relay R2 to be operated. Hence, under normal conditions, the armatures of relays R and R2 remain in the position illustrated.

If the just described circuit should be broken 45 for any reason, the relay R is deenergized and, therefore, its armature 25 moves into engagement with the contact at the adjacent end of conductor 2'5. As a result, a circuit is closed through the signal device S3, this circuit including the conductor Q leading from the positive terminal of battery B, the conductor 26, armature 25, conductor 2i, conductor 28, the signal device S3, conductor 29, and thence back to the negative terminal of the battery E by way of conductor it. The signal device S3 is actuated by the resultant current flow to indicate the presence or existence of an open circuit or loose connection such, for example, as might occur if, for any reason, the continuity of the core i should be disturbed.

Signal supervision As hereinbefore described, the conductor 9 extends from one terminal of the battery E to the conductor 23, to and through the energizing winding of signal device S2, the conductor 22, to and through the energizing winding of signal device S i, conductor 2 l, conductor 32, to and through the energizing winding of the remotely positioned signal device, conductor 3i, conductor is, winding of relay R3, conductor 29, armature E8 of relay R2, conductor 3t, and thence by way of conductor iii back to the negative terminal of the battery E.

In the circuit just described, the resistance characteristics of the various signal devices, on the one hand, and the winding characteristics of relay R3, on the other hand, are diiferent to an extent permitting operation of said relay R3 without causing operation of any of the signal devices. Accordingly, relay R3 maintains its armature 24 in the position illustrated.

Should the just described circuit be broken for any reason, the circuit through the winding of relay R3 is opened and this relay becomes deenergized to permit its armature 24 to engage the contact at theadjacent end of conductor 21. In response to such deenergization of relay R3, a circuit is completed through the signal device S3, this circuit extending by Way of conductor 9 from the positive terminal of battery E, conductor 23, armature 24 of relay R3, conductor 21, conductor 28, signal device S3, conductor 29, and. thence back to the negative terminal of battery E by way of the conductor iii. The signal device S3 is actuated by the resultant current flow to indicate the presence of any trouble, such as a broken wire or loose connection, in the signal devices S l S2 or the remotely positioned signal device connected to the conductors 3i and 32.

Battery supervision As hereinbefore described, the conductor 9 extends from one terminal of battery E and has one terminal of the Winding of relay Rl connected thereto, the other terminal of said winding being connected to the conductor is which leads back to the other terminal of the battery E. Due to the current flow in the circuit justdescribed, the relay Rl is maintained in energized condition and, accordingly, its armature l l is maintained in the position illustrated in Fig. 4.

Should the last described circuit be broken or should the current flow therein decrease to an abnormal extent, the relay BI is deenergized, its one armature i l moving into engagement with the contact at the end of conductor l3 and its other armature it moving into engagement with the contact at the end of conductor l4.

As a first result of r the just described deenergization of relay Rl a circuit is established from the positive terminal of battery Ei conductor l3,

conductor in, the signal device S, conductor l4,

armature it of relay Rl conductor l i) and thence back to the negative terminal of battery El by Way of the conductor l2. Accordingly, the signal device S is actuated to thereby indicate an abnormal condition of the battery E.

As a second result of the above described deenergization of relay Rl, the positive terminal of battery El is connected by conductor l3 to the armature ll of said relay Rl. The negative terminal oi battery E is permanently connected by the conductor to the conductor l0 and, accordingly, as will be obvious from Fig. 4, the armature l l of relay Rt, by moving to its deenergized position, substitutes the battery El for the batteryE. In the manner described above, an indication is obtained of an abnormal condition of the main battery E by current flowing from the auxiliary battery E l. At the same time, and during the persistence of said indication, the auxiliary battery El is substituted for the battery E to'thereby maintain the entire system in its operative condition.

When the battery E is restoredto its normal condition, relay RI is energized and, accordingly, the main battery E is restored to service, the battery El being automatically eliminated.

Fire detection As hereinbefore described in connection with the supervision of cable C and under normal conditions, the winding characteristics of relays. R and R2 are different to an extent permitting operation of the relay R but insufiicient to cause operation of the relay R2. Accordingly, under normal operating conditions, the armatures of relays R and. R2 are in the position illustrated 10 in Fig. 4.

Should the cable 0, in any section or region thereof, be exposed to fire or other abnormal high temperature conditions, a section of the core I becomes molten and moves or comes into engagement with the sheath 4 to thereby causea short circuit.

As a result, the prior existing circuit through the relay R is shunted out by the short circuiting core material and, due to the low resistance of said material as compared with the resistance of the winding of relay R, sufiicient current traverses the winding of relay R2 to cause energization of the same. Relay R2, accordingly, attracts its armatures Ill and l8. The latter, due to its movement from the contact at the end of conductor 28, opens the heretofore described circuit of the winding of relay R3, this circuit including the signal devices Sl, S2 and the remotely positioned signal device. As a result, relay R3 is deenergized and its armature 24 moves into engagement with the contact at the adjacent end of conductor 21.

Energization of relay R2, as described above, causes actuation of the signal devices S2 and SI, the energizing circuit for the latter extending from the positive terminal of battery E, conductor 9, conductor 23, signal device S2, conductor signal device Sl, conductor 2|, armature l8 of relay R2, conductor 30, and thence 0 by way of the conductor l0 back to the negative terminal of battery E.

Energization of relay R2 also causes actuation of the remotely positioned signal device, the energizing circuit therefor extending from the posi- 5 tive terminal of the main battery E, conductor 9, conductor 26, armature ll of relay RZ, conductor is, conductor 3B, the remotely positioned signal device, conductor 32, conductor 2|, armature l8 of relay R2, conductor 30, and thence by way of conductor l9 back to the negative terminal of battery E.

Deenergization of the relays R and R3 causes actuation of the signal device S3, the energizing circuit for the latter extending from the positive terminal of the main battery E, conductor s, conductor 23, armature 24 of relay R3, conductor El, conductor 28, the signal device S3, conductor 29, and thence back to the negative terminal of battery E by Way of conductor I0; a parallel circuit for energizing the signal device S3 extends from conductor 9, and includes the conductor 26, armature 25 of relay R, concluster 27, conductor 28, the signal device S3, and thence by Way of the conductor 29 back to the other battery conductor Ill.

be a fire gong of the vibrating type; that the signal device S2 be a fire gong of the single stroke type; and that the remotely positioned signal device be a gong having suitable characteristics.

As above stated, the signal device S3 operates in response to the presence of an open circuit in the main electrical circuit, namely, the circuit including the core and sleeve of the fire detecting cable C; furthermore, said signal device S3 operates in the event of trouble, as a broken wire or loose connection, in the signal devices SI, S2 or the remotely positioned signal device.

The signal device S indicates that the main battery E has become exhausted or that it is not properly supplying current to the fire detecting cable. As hereinbefore specifically pointed out, the auxiliary battery El is automatically substituted for the main battery E should the latter fail to function properly. The initiation of operation of the signal device S is effected as soon as such substitution has taken place and the operation thereof continues until the main battery E has been restored to service.

The signal devices S, S2 and the remotely positioned signal device are actuated upon the occurrence of a fire condition or a temperature simulation thereof in the immediate vicinity of cable 0. Obviously, the signal devices SI and S2 are of extreme importance in the operation of my system and, as pointed out above, they are under direct supervision so that corrective measures may be taken should they not be in operative condition. As an added measure of safety and as hereinbefore pointed out, the signal device SS is also operative in conjunction with the signal devices SI, S2 and the remotely positioned signal device upon the occurrence of a fire condition, as aforesaid.

The remotely positioned signal device may or may not be utilized as desired. In the event that this device is to be omitted, the armature H of relay B2 is blocked open and insulated in any suitable manner; at the same time, an electricity-conducting strap or jumper is connected across the conductors 3| and 32.

Ordinarily, it is desirable that both the signal devices Si and S2 be utilized in the manner described; however, under some circumstances it may be desirable toutilize but one of them. As pointed out above, the signal devices S and S3 are ordinary bells; obviously, however, the frequency of the sound produced by each should differ in an identifying manner.

Thus, in accordance with my invention, the simple act of inserting the plug el in the rec-eptacle e connects the fire detecting cable C on the car A in the supervised signaling circuit, the operation of which has just been described. In practice, the yard or depot should have a plurality of the cables K each terminating in a plug e1, the various cables K being connected in parallel relation as generally indicated in Fig. 4 wherein the conductors 8a, Ida, 9a and 1a of a second cable K are shown as connected to the respective conductors 8, H 9 and I. From the foregoing it follows that, with the depot or yard properly wired with the cables K, a large number of cars A may be disposed therein and with a cable plug 6! associated with a receptacle e on each car A, it results that all of the cars are connected in the central supervised signaling circuit. When the plug el is removed from the receptacle e, the circuit of Fig. 4 is the same as the circuit of Fig. 2 and, under this condition, the signal system is operative with respect to the battery 0 and the lamps d as hereinbefore described. This necessarily follows because with the plug cl removed from the receptacle e, the conductors f, g and h are open at their respective contact elements while the conductors a and a2 are connected at their contact element.

Although my invention, as regards the signaling lamps d, or equivalent, has been particularly described in connection with freight cars, it shall be understood that the invention is not to be thus limited since signaling arrangements as used on the car A are equally applicable to mail cars, baggage cars, express cars, or the like.

As regards that phase of my invention wherein a plurality of cars are to be located in a yard or depot with the temperature responsive devices thereon connected to a central signaling system, it shall be distinctly understood that the invention is of general application and that it is not to be limited to a car A such as disclosed. This is true because this broad idea is applicable to a fire detecting system for practically any vehicle, conveyance, carrier or the like. Thus, boats, yachts, aircraft, automobiles, trucks, or the like may be equipped with a fire indicating system such, for example, as illustrated in Figs. 1 and 2, and the anchorage, hangar, garage or the like may be equipped with a supervised signal system such as shown in Fig. 4 with a number of cables K to be connected individually to the fire indicating systems on the boat, aircraft, truck or the like.

Although the fire detecting system herein illustrated for use on the car A (a similar or equivalent system may be utilized on a boat, aircraft, truck or the like) is of the non-supervised type, the arrangement is such that the association of a plug at with a receptacle e places the temperature-responsive device, 1. e. the cable C in a supervised circuit. Therefore, each time that a plug el and receptacle 6 are thus associated, it follows that any open circuit or loose connection in the conductors of the cable C or in the immediately associated circuits causes the actuation of a single indicative of some non-operative arrangement in the fire detecting circuit.

The herein described cable C is adapted to exercise its control function when the core I becomes molten. Obviously, the constituents of said core l may be so chosen that this condition arises upon attainment of any predetermined temperature ambient to said cable C. In ordinary building installations, it has been found desirable for the core 1 to become molten at a temperature of about F. although, as will be understood, this may be varied within such latitude as may be desired.

In Fig. 4:, I have illustrated and described a supervisory signaling circuit of a particular character. It shall be understood that all features of this circuit need not be utilized for any given installation and, moreover, it shall be understood that other supervisory circuits may be substituted for the one herein disclosed. Thus, for example, the circuit illustrated in Fig. 2 of my aforesaid application Serial No. 388,143, filed August 2 1929 may be utilized in lieu of the supervisory circuit herein illustrated in Fig. 4.

Obviously, if desired, the arrangement of Figs. 1 and 2 may be employed without providing for connection of the cable of that arrangement to an external circuit by provision of the receptacle e, or equivalent.

As shown, an arragement is provided at the contact member al and .its associated contact element for automatically opening the circuit of battery 0 when a plug el is associated with a receptacle al. If desired, a manual switch may be employed in lieu of this automatic switch although the latter appears more desirable.

In the appended claims, the term vehicle shall be understood as generically comprehending either land, Water or air vehicles and more particularly, railroad cars, boats, yachts, aircraft, airplanes, automobiles, trucks or the like. Furthermore, the term fire condition shall be understood as meaning a fire condition literally or a temperature simulation thereof. Still further, expressions such as producing a signal shall be understood as of sufficient breadth to cover the operation of a suitable control device.

While the invention has been described with respect to certain particular preferred examples which give satisfactory results, it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent is: r

1. An electrical system for indicating the existence of undesirable thermal conditions in a vehicle comprising a vehicle circuit operative while the vehicle is in transit and including an electrically actuated signal mounted on the vehicle,

.a source of electrical energy carried by the vehicle and a thermo-responsive device comprising juxtaposed normally insulated conductors mounted on the vehicle for connecting the source of energy to operate the signal device upon the existence of abnormal thermal conditions, and an electrical circuit at a stopping place for the vehicle comprising a source of electrical energy, an electrically actuated device and means for disconnecting the thermo-responsive device from the vehicle circuit and connecting it in circuit Wit the electrically actuated device at the stopping place with the elements thereof forming a part of a closed circuit with the electrically actuated device and said second mentioned source of energy, the circuit being such that the current flowing therethrough normally operates the electrically actuated device.

2. An electrical system for indicating the existence of undesirable thermal conditions in a vehicle comprising a vehicle circuit operative While the vehicle is in transit and including an electrically actuated signal mounted on the vehicle, a source .of electrical energy carried by the vehicle and a thermo-responsive device comprising two juxtaposed normally insulated'conductors mounted on the vehicle for connecting the source of energy to operate the signal device on the existence of abnormal thermal conditions, and an electrical circuit at a stopping place for the vehicle comprising a source of electrical energy, two electrically actuated devices, one being operable on a lesser current than the other, and means for disconnecting the thermo-responsive device from the vehicle circuit and connecting it in circuit with the circuit at the stopping place with the elements thereof forming a part of a closed circuit with said second'mentioned source of energy and the two electrically actuated devlces.

3. An electrical system for indicating the existence of undesirable thermal conditions in a vehicle comprising a vehicle circuit operative while the vehicle is in transit and including an .electrically actuated signal mounted on the vehicle, a source of electrical energy carried by the vehicle and a therrno-responsive device mounted on the vehicle for connecting the source of energy to operate the signal device upon the existence or" abnormal thermal conditions including a pair of juxtaposed normally insulated electrical conductors one of which is fusible under abnormal thermal conditions, and an electrical circuit at a stopping place for the vehicle comprising a source of electrical energy, two electrically actuated devices, one being operable on a lesser current than the other, and means for disconnecting the thermo-responsive device from the vehicle circuit and connecting it in circuit with the circuit at the stopping place with the elements thereof forming a closed circuit with said second mentioned source of energy and the two electrically actuated devices.

4. An electrical system for indicating the existence of undesirable thermal conditions in a vehicle comprising a vehicle circuit operative while the vehicle is in transit and including an electrically actuated signal mounted on the vehicle, a source of electrical energy carried by the vehicle and a thermc-responsive device mounted on the vehicle, the thermo-responsive device including two normally separated conductors adapted to be electrically connected on the existence of abnormal thermal conditions and connect the source of energy to operate the signal, an electrical circuit at astopping place for the vehicle comprising a source of electrical en ergy, two electrically actuated devices, one being operable on a lesser current than the other, and means including a pair of complementary plug connectors one connected into the vehicle circuit and the other connected into the circuit at the stopping place for disconnecting the thermoresponsive device from the vehicle circuit and interconnecting it with the circuit at the stopping place with the conductors of the thermo-responsive device forming a part of the closed circuit including said second mentioned source of energy and the two electrically actuated devices.

WILLIAM D. LINDSEY. 

